1. UNDERSTANDING
COMPUTER

2. A computer is one of the most brilliant inventions of mankind.
Thanks to the computer technology, we were able to achieve
storage and processing of huge amounts of data; we could rest our
brains by employing computer memory capacities for storing
information. Due to computers, we have been able to speed up
daily work, carry out critical transactions and achieve accuracy and
precision in work. Computers of the earlier years were of the size of
a large room and were required to consume huge amounts of
electric power. However, with the advancing technology, computers
have shrunk to the size of a small watch. Depending on the
processing power and size of computers, they have been classified
under various types. Let us look at the classification of computers.

3. Different Types of Computers
Based on the operational principle of computers, they are categorized as
analog, digital and hybrid computers.
Analog Computers: These are
almost extinct today. These are
different from a digital computer
because an analog computer
can perform several
mathematical operations
simultaneously. It uses
continuous variables for
mathematical operations and
utilizes mechanical or electrical
energy.

4. Digital Computers
They use digital circuits and are designed to
operate on two states, namely bits 0 and 1. They
are analogous to states ON and OFF. Data on
these computers is represented as a series of 0s
and 1s. Digital computers are suitable for
complex computation and have higher processing
speeds. They are programmable. Digital
computers are either general purpose computers
or special purpose ones. Special purpose
computers, as their name suggests, are designed
for specific types of data processing while general
purpose computers are meant for general use.

5. Hybrid Computers
These computers are a
combination of both digital and
analog computers. In this type of
computers, the digital segments
perform process control by
conversion of analog signals to
digital ones.

6. Classification of Computers
The following are the classification of the different types of computers based on their sizes and
functionalities:
Mainframe Computers: Large
organizations use mainframes for
highly critical applications such as
bulk data processing and ERP.
Most of the mainframe computers
have the capacities to host
multiple operating systems and
operate as a number of virtual
machines and can substitute for
several small servers.

7. Minicomputers: In terms of size and
processing capacity, minicomputers lie
in between mainframes and
microcomputers. Minicomputers are
also called mid-range systems or
workstations. The term began to be
popularly used in the 1960s to refer to
relatively smaller third generation
computers.

8. Servers: They are computers designed
to provide services to client machines in
a computer network. They have larger
storage capacities and powerful
processors. Running on them are
programs that serve client requests and
allocate resources like memory and
time to client machines. Usually they
are very large in size, as they have
large processors and many hard drives.
They are designed to be fail-safe and
resistant to crash.

9. Supercomputers: The highly
calculation-intensive tasks can be
effectively performed by means of
supercomputers. Quantum physics,
mechanics, weather forecasting,
molecular theory are best studied
by means of supercomputers. Their
ability of parallel processing and
their well-designed memory
hierarchy give the supercomputers,
large transaction processing
powers.

11. Microcomputers: A computer with a
microprocessor and its central processing
unit it is known as a microcomputer. They
do not occupy space as much as
mainframes do. When supplemented with
a keyboard and a mouse, microcomputers
can be called personal computers. A
monitor, a keyboard and other similar
input output devices, computer memory in
the form of RAM and a power supply unit
come packaged in a microcomputer.
These computers can fit on desks or
tables and prove to be the best choice for
single-user tasks.

12. Personal computers come in different forms such as desktops, laptops and
personal digital assistants (refer to Figure 3). Let us look at each of these
types of computers.
Desktops: A desktop is intended to
be used on a single location. The
spare parts of a desktop computer
are readily available at relatively
lower costs. Power consumption is
not as critical as that in laptops.
Desktops are widely popular for daily
use in the workplace and households.

13. Laptops: Similar in
operation to desktops, laptop
computers are miniaturized
and optimized for mobile use.
Laptops run on a single
battery or an external
adapter that charges the
computer batteries.

14. Netbooks: They fall in the
category of laptops, but are
inexpensive and relatively
smaller in size. They had a
smaller feature set and lesser
capacities in comparison to
regular laptops, at the time
they came into the market.

15. Personal Digital Assistants (PDAs): It
is a handheld computer and popularly
known as a palmtop. It has a touch
screen and a memory card for storage
of data. PDAs can also be used as
portable audio players, web browsers
and smart phones. Most of them can
access the Internet by means of
Bluetooth or Wi-Fi communication.

16. Tablet Computers: Tablets are
mobile computers that are very
handy to use. They use the touch
screen technology. Tablets come
with an onscreen keyboard or use
a stylus or a digital pen. Apple's
iPod redefined the class of tablet
computers.

17. Wearable Computers: A record-setting step in
the evolution of computers was the creation of
wearable computers. These computers can be
worn on the body and are often used in the study
of behavior modeling and human health. Military
and health professionals have incorporated
wearable computers into their daily routine, as a
part of such studies. When the users' hands and
sensory organs are engaged in other activities,
wearable computers are of great help in tracking
human actions. Wearable computers do not have
to be turned on and off and remain in operation
without user intervention.